Interpretive Summary: Beef carcass contamination is a direct result of pathogen transfer from cattle hides harboring disease causing bacteria. Hide contamination occurs from direct and indirect fecal contamination in cattle production and processing plant holding pen environments. In each of these environments, individual animals shedding E. coli O157:H7 at high levels (“super shedders”) can have a disproportionate effect on cattle hide and subsequent carcass contamination. It is not known what criteria must be met to cause the super shedding phenomenon. Understanding the factors that play a role in super shedding will aid in minimizing or eliminating the super shedding population. Removal of the super shedders from the cattle population will reduce E. coli O157:H7 transmission in cattle-associated environments, resulting in much lower risk of beef carcass contamination and a safer finished product.

Technical Abstract:
Beef carcass contamination is a direct result of pathogen transfer from cattle hides harboring organisms such as enterohemorrhagic E. coli. Hide contamination occurs from direct and indirect fecal contamination in cattle production and lairage environments. In each of these environments, individual animals shedding E. coli O157:H7 at high levels (>104 CFU/g of feces, “super shedders”) can have a disproportionate effect on cattle hide and subsequent carcass contamination. It is not known what criteria must be met to cause the super shedding phenomenon. Understanding the factors that play a role in super shedding will aid in minimizing or eliminating the super shedding population. Removal of the super shedders from the cattle population will reduce E. coli O157:H7 transmission in the production and lairage environments, resulting in much lower risk of beef carcass contamination and a safer finished product.